Mounting an airbag apparatus configured to absorb an impact applied on an occupant by inflating and deploying an airbag in a cabin in case of collision or sudden deceleration on a vehicle such as an automotive vehicle is becoming popular. As such an airbag apparatus, various types such as a driver airbag apparatus mounted in the interior of a steering, a passenger airbag apparatus mounted in the interior of an instrument panel, side airbag apparatuses mounted in the interiors of side surface portions of a vehicle or in the interiors of seats, curtain airbag apparatuses mounted in the interiors of upper portions of doors, knee airbag apparatuses corresponding to knees of the occupants, a pedestrian airbag apparatus mounted in the interior of a portion under a hood are developed and employed. Such an airbag apparatus is generally included a gas generator configured to generate gas under predetermined conditions, an airbag configured to be inflated and deployed by being connected to the gas generator, and a retainer configured to store the airbag. Also, an outer shell which forms the airbag might be formed with an air discharge port referred to as a vent hole. The vent hole has functions to prevent an internal pressure of the airbag from becoming excessively high and to alleviate an impact by discharging gas in the airbag when the occupant comes into contact with the airbag.
In the airbag apparatus formed with the vent hole as described above, there is a problem such that the pressure loss is large since gas is discharged from the vent hole during the inflation and deployment of the airbag. As the airbag apparatus configured to solve the problem as described above, for example, those disclosed in Patent Document 1 and Patent Document 2 are already proposed.
The airbag apparatus disclosed in Patent Document 1 includes a strap secured at one end thereof to an inner peripheral surface of a ceiling portion of the airbag and secured at the other end thereof to a peripheral edge portion of a vent hole so as to close up the vent hole by being inserted therethrough from the side of the inner peripheral surface to the side of an outer peripheral surface of the airbag in the vicinity of the vent hole. This strap acts to close up the vent hole by being pulled while the airbag is being inflated and deployed, and to be loosened to open the vent hole when the occupant comes into contact with the airbag.
Also, the airbag apparatus disclosed in Patent Document 2 discloses the one in which an air-discharging tube is connected to an outer shell of the airbag (for example, FIGS. 11A, 11B) in addition to the one having the similar configuration to the one disclosed in Patent Document 1 (for example, FIG. 5). The air-discharging tube is pulled inwardly of the airbag by the strap, and the air-discharging tube is configured to be opened to the outside of the airbag and act as the vent hole when an anchor which fixes the strap is disengaged.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 6-127330
[Patent Document 2] U.S. Pat. No. 6,648,371B2